Translations:Sampling geophysical data/10/en

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As another example, a sine wave of 125 Hz has the alias of 125 – 250 = –125 Hz in the sampled signal. Because we are dealing with a real-valued signal, the negative frequency –125 Hz is the same as the positive frequency +125 Hz. Thus the Nyquist frequency does not alias, as we would expect, because it lies in the Nyquist range. A sine wave of 135 Hz has the alias of 135 –250 = –115 Hz in the sample signal. Because we are dealing with a real-valued signal, the frequency –115 Hz is the same as the frequency +115 Hz. Thus, the frequency +135 Hz aliases to the frequency 115 Hz, which we see lies in the Nyquist range.